Question

Consider the following struct:

    public struct vip
    {
        string email;
        string name;
        int category;

        public vip(string email, int category, string name = "")
        {
            this.email = email;
            this.name = name;
            this.category = category;
        }
    }

Is there a performance difference between the following two calls?

var e = new vip(email: "foo", name: "bar", category: 32);

var e = new vip("foo", 32, "bar");

Is there a difference if there are no optional parameters defined?

Answer 1

There’s a compile-time cost, but not a runtime one…and the compile time is very, very minute.

Like extension methods or auto-implemented properties, this is just magic the compiler does, but in reality generates the same IL we’re all familiar with and have been using for years.

Think about it this way, if you’re using all the parameters, the compiler would call the method using all of them, if not, it would generate something like this behind the scenes:

 var e = new vip(email: "foo", category: 32); //calling

 //generated, this is what it's actually saving you from writing
 public vip(string email, int category) : this(email, category, "bar") { }